[time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

[Rice, Hugh (IPH Writing Systems)]

Luca wrote:

> There is a little strangeness: the wave clipper darlington transistor Q1 is
> marked as 1854-0611, equivalent to the standard darlington 2N6055. But why
> there is a simple 2N3055 in the picture? Some sort of version update fail?

One other reader (Ian) pointed out this same discrepancy, and there clearly is a part number error somewhere.    I remember using the Darlington device on purpose, because with its higher gain, it took a less base current to accomplish the wave clipper job I used it for.

As you can see, getting these details right in documentation is challenging.  I remember working on it pretty hard, and this one got past me.   Who knows, for the photo shoot of the PCA, I may have just stuck the wrong part in there because I didn’t have the right one on had that day.  “Hey, no one will notice that the stamping on the transistor doesn’t match the parts list.   I’ll bet no one will look at this schematic carefully anyway.   Take the picture.”    Never knowing that 30 years later, some “time-nut” would scrutinize the photo vs. the schematic, and point out to me “those numbers don’t match!”

Putting things in writing and disclosing it to the public is a risky undertaking!   😊

Best wishes,
Hugh




From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of Luca
Sent: Sunday, February 10, 2019 8:55 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Subject: [time-nuts] HP Stories: Battery Chargers, and a fading idolization of HP

Thanks Hugh for the story, and thanks for the schematic!
Quite interesting.
There is a little strangeness: the wave clipper darlington transistor Q1 is
marked as 1854-0611, equivalent to the standard darlington 2N6055. But why
there is a simple 2N3055 in the picture? Some sort of version update fail?
Thanks
Cheers
Luca
iw2lje

Il giorno sabato 9 febbraio 2019, Rice, Hugh (IPH Writing Systems) <
hugh.rice at hp.com<mailto:hugh.rice at hp.com>> ha scritto: